In recent years, as information technology (IT) has been introduced in various fields, the necessity of a data center that provides customers with a line connecting to a network, maintenance and operation service, and the like has increased.
Generally, many servers are installed in a server room of a data center and therefore the amount of heat generation is high. In this server room, in order to cause the servers to operate normally, it is necessary to appropriately perform air conditioning on the server room and maintain an environmental condition of a predetermined range.
As a technique of cooling the inside of a room in which many computers are installed such as the server room of the data center, there is an air conditioning apparatus configured to suck air from a lower space of the inside of the room and blow the air to an upper space so that the air is sucked into a space above a server rack.
Using this technique, a temperature gradient of the entire server room is reduced, and a variation in a supply air temperature is reduced, and thus air conditioning control can be efficiently performed.
However, when a load of an air conditioning target is an information device as in the server room of the data center, since most of loads are sensible heat loads, it is desirable that setting temperature and humidity are within a predetermined range, and since CO2 is not generated from a load, air ventilation for preventing an increase in CO2 density is unnecessary, that is, the server room has a feature different from a state inside a general building. However, in the past, air conditioning control corresponding to this feature is not performed, and thus there is a problem in that energy may be uselessly expended. For this reason, air conditioning apparatuses for server room management using outdoor air for implementing an air supply condition allowed in American society of heating, refrigerating and air-Conditioning engineers (ASHREA) 2008 have been already proposed. However, it is possible to further save energy using an air supply condition allowed in ASHREA 2011 in which the air supply condition on the server room is recently mitigated.